1. Field of the Invention
The present invention pertains to the art of conveyors and, more particularly, to a conveyor belt incorporating open conveyor modules which are constructed in a manner which enhances cleanability thereof.
2. Discussion of the Prior Art
Conveyor belts constructed in various manners are known in the art. Many of these conveyor belts are formed from interconnecting symmetric conveyor modules by means of a plurality of longitudinally spaced rods which extend through respective portions of the modules. The rods are interconnected at their respective ends by linkages which cooperate with one or more driving units for moving the conveyor belt along a desired path.
When such conveyor belts are used in particular environments, such as in carrying food items for human consumption or other applications requiring sanitary operating conditions, the conveyor belts must be cleaned and inspected regularly for cleanliness. In many industries, government regulations require periodic inspection of conveyor cleanliness. When used in such environments, it is commonplace to incorporate a wash unit for the conveyor belt along the conveying path, generally in a zone immediately adjacent a work station where items are either initially placed on the conveyor or removed therefrom. By way of example, FIG. 1 illustrates a typical closed cooler compartment 5 used for refrigerating various food items placed upon a conveyor belt 8. In order to maximize storage capacity, such compartments 5 generally are constructed to permit movement of the conveyor belt 8 in a linear direction, as well as taking a helical spiralling path, such as generally indicated at 10, wherein successive layers of conveyor belt 8 are arranged atop one another. After conveyor belt 8 exits compartment 5 and reverses direction to again enter compartment 5, conveyor belt 8 proceeds through a washing unit generally indicated at 15. Washing unit 15 can spray water or other cleaning solutions on either one side or both sides of conveyor belt 8.
Depending upon the particular construction of the conveyor belt, the effectiveness of this cleaning operation can vary. Clearly, a conveyor belt formed of open modular units will permit the sanitizing fluid to flow therethrough which aids the cleaning process, however, there are various hard-to-clean joints, crevices and other debris trapping areas associated with known conveyor belts which can lead to unsanitary conditions. In addition, the actual material utilized in constructing the conveyor belt and the manner in which they are assembled in accordance with the known prior art often results in wear debris. The creation of wear debris can be an extremely serious problem if, for example, an open conveyor arrangement is used with a spiral food processing unit such that any debris from an upper conveyor belt layer can fall on food items or the like located on a lower conveyor belt layer. This can be a particular problem when the conveyor belts are formed entirely from metal with limited clearances between relatively moving parts.
One major debris trapping area associated with known conveyor belts incorporating open conveyor modules interconnected by longitudinally spaced rods in the manner described above, is the contact zone between the rods and front walls of forwardly extending link ends of the conveyor modules. In known prior art conveyor belt arrangements, the rods have line contact across the entire inner surface of the forwardly and rearwardly extending link ends such that the force transmitted through the drive units to the rods are transmitted to the modules. This keeps the rod and module surface contact areas tightly together, causing frictional wear debris when the belt rotates when negotiating vertical change of direction pulleys. This tight contact prevents effective removal of any wear debris and food particles because the engagement of rod and module blocks one side of the assembly to the wash spray from the other side. These surface contact areas represent a fair percentage of the overall surface area of the modules and therefore the inability to clean in these areas can result in less than desirable operating conditions from a sanitary/cleanliness standpoint.
Another problem associated with known conveyor belts that are adapted to conform to spiralling paths by the collapsing of the conveyor modules progressively towards an inner radial zone is that, since the outer radial drive links or modules are fully extended with tension applied thereto and the inner radial drive links or modules are collapsed and carry no tension, if relative rotation between the drive links or modules carried by any given rod is permitted, buckling of the conveyor modules can occur. If such buckling occurs in certain environments such as a spiral freezing unit, the articles placed on the conveyor belt can take an undesired shape and can create problems in packaging of the items. In many known conveyor belts utilizing metal drive linkages, heads are formed at the end of the rods and these heads are welded to the drive linkages. Unfortunately, due to fatigue loading, these welds often break which give rise to the problems outlined above, as well as repair costs and undesired down time of the conveying unit. Furthermore, these heads often evince burrs or the like which can damage the surfaces of frictional drive drums commonly used at the inner radial side of such conveyor belts in spiral cooling units.
Therefore, there exists a need in the art for a conveyor belt that can be used over both linear and curvilinear conveying paths which is constructed to enhance the cleanability of the conveyor assembly, as well as to minimize additional sanitary and operational deficiencies in known conveyor belt arrangements.